void init(list * l){
    //not working, but sensible
    l = malloc(sizeof(list));
    if (l == NULL) {
        exit(-1);
    }
    l->val = NULL;
    l->next = NULL;

    /*
    //working but silly (and proabably memory problems)
    list head = *l;
    head.val = NULL;
    head.next = NULL;
    *l = head;
    */
}